Sensors are useful for measuring analytes in many applications, including clinical, environmental, and process monitoring. In many of these applications, it is desirable to perform the measurement using a small liquid sample volume. Correct positioning of the sample aliquot over the transducer element or reactive area of the sensor is crucial to obtaining an accurate result.
For example, sensors for electrochemical fluid analysis applications (such as blood glucose testing) rely on proper fluid placement over electrodes, or “active” portions of the sensors. Fluid location is also important in an optically based sensor. If the fluid sample is not located within the light path, the system may yield an inaccurate result. Fluid placement within a sensor (for example, within a capillary cavity) thus becomes an important factor in achieving accurate measurements.
Many factors affect fluid placement within a sensor. For example, capillary geometry, internal capillary surface wettability, sample size, and composition all affect fluid placement. The impact of vent shape and location has been overlooked, as it pertains to fluid placement within a capillary-fill sensor. There is a need for fluid analysis sensors wherein the location and shape of vents are designed to effect proper fluid placement and thereby minimize required sample volume and increase accuracy of readings.